Heat exchanger



July 20 1926.

G. D. MANTLE HEAT EXCHANGER Filed May 28, 1924 2 Sheets-Sheet 1 mu W M I a, i

July 20,1926. 1,593,537

G. D. MANTLE HEAT EXCHANGER Patented July 20, 1926.

UNITED STATES PATENT: omen:

. GREGORY D. IANTLE, OI PITTSBURGH, PENNSYLVANIA,

ASSIGNOR we ran cfioarzwe column, or rxrrsnuaemrnmwsnvanu, A. ooaroaxrron or nnmwann.

- mu: nxcmenn. I

Application filed May as, 1924. Serial a... 710,371.

This invention'relates broadly to heat ex changers, and more particularl to recuperators of the type in which t gas to be heated, usually air, and the heating gas or gases flow continiiously in contact with opposite sides of metal tubes. Recuperators ofthis type as heretofore constructed have not been economical for use except with comparatively low temperatures, as the tubes would quickly burn out when subjected to hi? temperatures.

- y the present invention, I have provided a heat exchanger in which the air can be heated to a high degree without danger of burning out the tubes. In; the referred embodiment of the invention Which is illustrated in the accompanying drawings, the cold air enters the recuperator adjacent one end thereof and is caused to flow at relatix'ely hi h velocity in contact with one surface 0% the hottest ortion of the tubes. The partially heated air is then conducted out of contact with the intermediate portion of the tubes to the other end of the recuperator and caused to flow in contact with one surface of the coldest portion of the tubes. Finally, the partially-heated air is conducted in contact with the intermediate portion of the tubes and passes out of the 80 recuperator at a point adjacent the hottest portion of the tubes. ,The hot gases'enter the recuperator at the same end thereof as the cold air and leave it at its other end. This method of operating the recuperator enables the cold air to rapidly absorb the heat from the hottest end portions of the tubes, so that gases entering therecuperator at a relatively high temperature will not heat any portionv of the tubes to an extent 40 to'endanger burning them out. The tubes and the header at the intake erid of the recuperator are preferably constructed of calorized steel, thereby further ensuring long life for-the recuperator;

v The invention embodies, in addition to the above, various constructional features which cooperate to produce a recuperator of high efliciency. These features will be fully pointed out in the following description and" covered in the claims.

In; the drawings- Figure 1 is a vertical sectional view, partly broken away, of a cuperator embodyin 'my lnvention;

Figure 2 is a top p an View thereof; and Figure 3 is a section on the line III-III of Figure 1.

Figure 4 is a, detail sectional view of my improved expansion joint.

The recuperator as illustratedcomprises a preferred form of re vertical metal shell 2 of rectangular form in cross section. At the upper and lower ends of the shell are header plates 3 and 4. Arranged within the shell is a series of vertically extending metal tubes 5. These tubes extend through the header plate 3 and have their upper ends substantially flush with the upper surface of said plate. The tubes also extend through the header plate 4but project a slight distance below the same and have their lower ends positioned in openings 6 in a base plate 7. The tubes 5 and base plate, as already mentioned, are preferably constructed from calorized steel.

The bottom portion of the shell is surrounded by a metal wind box 8 of rectangular form in cross section and having its vertical walls spaced from the sides of the shell to provide a relatively narrow duct 9 entirely surrounding the lower portion of the shell. At its upper end, the wind box is provided with an inwardly extending flange 10, the inner edge of which engages the sides of the recuperator and is secured thereto. At its lower end, the wind box is provided with an outwardly extending flange 11 which rests upon the base plate 7 Fitted in the angle between the flange 11 and the vertical walls of the wind box is a reinforcing angle member 12. The wind box is provided at one side thereof with an inlet connection 13. The header plate 4 extends to the side of the wind box having the inlet connection 13'and also to the two adjacent sides thereof, but at the side of the wind box opposite the side having the inlet connection, the header plate terminates flush with the corresponding side of the shell 2, thereby providing an opening 14 between the last mentioned side, of the wind box and the adjacent edge of the header plate for the air to pass from the duct 9 into the space 15 be tween theheader plate 4 and the base plate 7. The cold air enters the recuperator through the inlet connection 13 and then divides and flows to the right and to the left in the direction of the arrows through the duct 9 to the opposite side of the recuperator and then flows downwardly through the opening 14 into the space 15 between the header plate 4 and base plate 7.

The shell 2 is provided with a vertical partition plate 16 s aced from the side thereof ad]acent the inlet connection 13 and extendin the full distance between the adjacent si es of the shell to provide a vertical air duct 17. This partition plate extends from the header late 4 and terminates a considerable distance below the header plate 3. The air duct 17 commumcates at its lower end with the space 15 through an opening 18 in the header plate 4.

Extending horizontally from the upper edgeportion of the partition plate 16 toward but terminating short of the opposite side ofthe shell 2 is a bafile plate 19 forming a space 20 between the same and the header p ate 3. The air flows from the space 15 upwardly through the duct 17 and -then flows through the space 20 in contact with the upper end portions of the tubes. It then flows downwardly through the shell in contact with the intermediate portion of the tubes and passes out of the recuperator through an outlet connection 21 in the side of the shell 2 opposite the side having the inlet connection 13 for the cold air. In

order to compel the air to flow back and forth in contact with the intermediate ortion of the tubes so as to' absorb the eat uniformly from all of them, a series of additional horizontal bafiles 22 are provided, these bafiies being arranged in staggered relation and extending alternately from the side of the shell 2 having the outlet connection 21 and from the vertical partition late 16. The' air duct 17, being situated etween the tubes and one side 0 the shell 2, prevents loss of any-material amount of heat by radiation from the tubes at that side of the shell.

The upper ends of the tubes 5 are secured in the header plate 3 in any suitable manner and the bafile plates 19 and 22 are supported from the header plate 3 by a series of vertical rods 23 and separator pipes 24 surroundin the rods and interposed between the iaflles and between the upper bafile 19 and the header plate 3 for maintaining the baflles in proper horizontal position. The rods 23 are screw threaded at their ends for the reception of nuts 25.

The recuperator may be placed in any suitable masonry setting whereby the hot ases will enter the tubes 5 throu h their ower ends and flow u wardly theret rough. It will be apparent t at the tubes and the shell 2 will be subjected to unequal amounts of expansion and contraction during the olpleration of the recuperator. In order that t 's unequal expansion and contraction may take place without in'urious effect upon the recuperator, the hea er plate 3 is not ri idly attached to the upper end of the shel 2 but is connected thereto by a bellows-like connection consisting of annular plates 26 and spacer rin 27, as shown in Figure 4. This construction provides an expansion joint between the upper end of the shell and the header plate 3, permitting the header plate to -move bodily with respect to the shell in following the expansion and contraction of the tubes 5. By reason of this expansion joint, the plates and tubes are not subjected to any injurious strains owing to unequal conditions of expansion and contraction of the parts when the re cuperator is in operation.

In order to reinforce the metal shell 2. the sides thereof have welded thereto at intervals Ts 28.

In the operation of the recuperator, the base plate 7 and the end portions of the tubes extending betweenthe header plate 4 and base plate will be subjected to the highest temperatures. Since, however, the space 15 is relativel restricted, the cold air will flow at relative y high velocity through this space and will prevent the base plate 7 and the lower end portions of the tubes extending between the base plate and header plate 4 from becoming heated to such an extent as to endanger their burning out. The air is forced to flow along the base plate 7 so that the base plate and the extreme lower ends of the tubes are effectively cooled. Moreover, the higher velocity of the air through the space 15, which is considerably reater than the average velocity of the air through the remainder of the recuperator, causes better heat exchange, since the rate of heat exchange increases with the velocity of the air. Since the end portions of the tubes first heated by the hot gases are cooled in this manner by the incoming air, it is possible by this method of operating the recuperator to heat air to a higher temperature than has heretofore been possible without heating any portion of the tubes to a tube destroying tem erature. v

T e wind box surrounding the lower por tion of the shell prevents any substantial loss of heat due to conduction from the base plate 7 to the lower portion of the shell. It will be apparent that the cold air flowing through t e duct 9 between the sides of the wind box and the sides of the shell will rapidly absorb any heat passing by conduction from the highly heated base plate 7 to the sides of the wind box and sides of the shell, thereby preventing the loss of any considerable amount of heat to the outside an.

zontally if desired. It will also be apparent that the hot gases could be caused to pass in contact with the outer surfaces of the tubes and the air to be heated caused to flow through the tubes. These and other changes in the details of construction and in the method\of operating the recuperator are contemplated'as being within the spirit of the invention andthe scope of the appended clailrls. a

T application is a continuation in part of m 'co-pending' application, Serial No. 659,859, filed August 29, 1923. a

1. Themthod of heating a gas by passing a hot gas and the gas to be heated over opposite sides of heat transfer means, comprising bringing the gas to be heated in contactwith a hotter portion of such means, then passing it in contact with a colder portionthereof, and thereafter passing it in' contact with an intermediate portion of said means, substantially as described.

2. The method of heating a gas by passing a hot gas and the gas to be heated over op-' osite sides of heat transfer means, compris mg bringing the gas to be heated in contact with a hotter portion of such means, then passing it in contact with a colder portion thereof, and thereafter passing it in contact with an intermediate portion of said means,

the gas to be heated being passed in contact with the hotter portion of said means at a substantially greater velocity than the average velocity of the gas when passing in contact with the remaining portions of the heat transfer means, substantially as described. 3. The method of heating a gas by effecting a heat exchangebetween the gas and a hot gas, comprising passing the hot gas through metal tubes, and passing the gas to be heated over the hot end portion of the. tubes, then passing it over a colder portion thereof, and thereafter passing it in contact with an intermediate portion thereof, substantially as described. I

4. The method of heating a gas by effecting a heat exchange between the gas and a hot gas, comprising passing the hot gas through metal tubes, and passing the as to be heated across the hotter end P0117101!- of the tubes, then passing the partially heated gas across the colder end portion thereof, and thereafter passing it in contact with the intermediate portion of the tubes toward the hotter end portion thereof, substantially as described.

rection opposite to the flow of the heating g'as therethrough, substantially as described. 6. A heat exchanger comprising heat transfer means adapted to effect a heat exchange between .a gas to be heated and a hot gas flowing over opposite surfaces thereof,

comprising means for bringing the gas to.

be heated into contactwith a hotter portion of the heat transfer means,'-means for passing the. partially heated gas incontact with a colder portion of the heat transfer means, and means for thereafter passing it in contactwith an intermediate portion of the heat transfer means, the construction bein such that the gas to be heated is caused to ow in contact with the hotter portion of the heat transfer means at a substantially greater velocity than the average velocity of the gas when passing in contact with the remaimng portions of the heat transfer means, substantially as described. 7

7. A heat exchanger, comprising a plurality of conducting tubes adapted to be heated by the flow of a hot gas in contact with one surface thereof, and separate means whereby the gas to be heated is caused to flow ill-contact with the hotter portion of the tubes, then in contact with the colder portion thereof, and thereafter is conducted towards the hotter portion of the tubes in contact with an intermediate po rtion thereof, substantially as described. i

8. A heat exchanger, comprising a, plurality of conducting tubes for a heating gas,

means defining a restricted chamber through 9. A heat exchanger, comprising a pair of spaced heads, a plurality of conducting tubes for a-heating gas extending between said heads and having their ends positioned in openings therein, an intermediate head adjacent the head at the intake ends of the tubes, theconstruction being such that the gas to be heated flows through the space between said last mentioned heads and is -therein initially brought into contact with the hotter "end portions of the tubes, means for conductin the partially heated gas out of contact wi h the tubes toward the outlet ends thereof and then assin it in contact with the colder end portions 0 the tubes, and means for thereafter producing a flow of the partially heated gas in contact with the intermediate portions of the tubes and in a direction counter to the direction of flow of the heating gas through the tubes, substantially as described.

10. A heat exchanger, comprising a vertically extending shell, heads adjacent the upr and lower ends of said shell, a plurality of vertically extending conducting tubes for the heating gas arranged within said shell and having their ends positioned in openings' in said heads, an intermediate head secured to the lower end of said shell and having the tubes extending therethrough and defining a space between itself and the bottom head through which the gas to be heated flows, a duct communicating at its lower end with said space and extending vertically within the shell for conductingthe partially heated gas from said space to the upper end portions of the tubes, baflle means within said shell for .causing the partially heated gas to flow from the upper end of said duct across the u per end portions of the tubes and then bac and forth in contact with the iiitermediate portions thereof toward the lower ends of the tubes, and an outlet for the heated gas adjacent the lower end of said" shell, substantially as described.

11. A heat exchanger, comprising a vertically extending shell, a plurality of conducting tubes for a heating gas extending vertically within said shell, a casing surrounding the lower portion of said shell through which the gas to be heated flows prior to being brought into contact with the tubes, and means for conducting the gas to be heated from said casing in contact with said tubes, substantially as described.

12. A heat exchanger, comprising a vertically extending shell, a plurality of conducting tubes for a heating gas extending vertically within said shell, a casing surrounding the'lower portion of said shell through which the gas to be heated flows prior to being brought into contact with the tubes, and means for conducting the gas to be heated from said casing first in contact with the hotter end portions of said tubes and thereafter in contact with a colder portion thereof, substantially as described.

13. A heat exchanger, comprising a vertically extending shell having heads secured to its upper and lower ends, a plurality of conducting tubes for a heating gas extending vertically within said shell and having their ends positioned in openings in said heads, a casing surrounding the lower portion of with said shell thro h which the as to be heated flows rior to ing broug t into contact e tubes, means for conducting the gas to be heated from said casing across the lower end portions of the tubes, and means for thereafter conducting the artially heated gas upwardly within the s ell to the upper end portions of the tubes and then in contact with said upper end portions and then in contact with the intermediate rtions of the tubes, substantially as descri d.

14. A heat exchanger, comprising a vertically'extendin metal shell having metal heads connec to its upper and lower ends, a plurality of metal tubes 'extendin vertically within said shell and throng said heads, a metal base plate arranged below the lower head and in spaced relation thereto, said base plate having the lower ends of the tubes positioned in openings therein, a metal casing supported on said base plate and surrounding the lower por-v tion of said shell, said casing having an inlet for the gas to be heated and communicating with t e space between the lower head and the base late, an outlet connection secured to the ower portion of the shell and extending through said casing, and means for conducing the partially heated gas from the space between the lower head and the base plate upwardly within the shell out of contact with the intermediate portions of the tubes, then across the upper end portions of the tubes and then from said u per end rtions in contact with the interme iate portions of the tubes to said outlet connection, substantially as described.

15. A heat exchanger, comprising a vertically extending metal shell, a metal head at the upper end of said shell, metallic sealing connecting means between said head and the upper end of the shell rmitting said head to move bodily with respect to said 'shell in the direction of the axis thereof, said sealing means com risa plurality of metal annular p ates w ereof the alternate outer and inner edges of adjacent plates are sealed together, thereby forming an expansible bellows, a plurality of conducting tubes for the heatin gas extending vertically, within said she and having their upper end portions secured to said head and extending through openings therein, and means for conducting the gas to be heated through said exchanger in contact with said tubes, substantially as described.

l6. A heat exchanger, comprising heat transfer means adapted to effect a heat exchange between a gas to be heated and a hot gas flowing over opposite surfaces thereof, comprising means for bringing the gas to be heated into contact with a hotter portion of the heat transfer means, means for passing the partially heated gas in contact wRh a colder. portion of the heat transfer means, and means for thereafter passing it in contact with an intermediate portion of the heat transfer means, substantially as described.

17. The method of heating a as by passing a hot as and the gas to be eated over opposite sides of heat transfer means, comprising bringing the gas to be heated in contact with that portion of the heat transfer means where the hot gas enters then passsing it to that part of such means Where the hot gas is discharged, and thereafter passing it in contact with intermediate portions of said means, substantially as de scribed.

18. A heat exchanger, comprising ametal shell, a metal head at one end of said shell, metallic sealing connecting means between said head and the end of the shell permitting the head to move bodily with respect to the shell in the direction of the axis thereof, said sealing means comprising a plurality of metal annular plates whereof the alternate outer and inner edges of adjacent plates are sealed together, thereby formin an expansible bellows, a plurality of con uctin tubes for the heating gas extending within said shell and havmg their end" ortions secured to said head and .ex tending throu h openings therein, and means for con noting the gas to be heated through said exchanger in contact with said tubes, substantially as described.

In testimony whereof I have hereunto setmy hand.

GREGORY D, MANTLE. 

